No-load loss
830 W
Transformer Efficiency & CO₂ Calculator
Estimate a transformer's annual losses and CO₂ emissions from its efficiency level, load factor and hours — and compare efficiency grades to see the carbon impact.
Result
Enter your load → get a full design & BOM in seconds
Sample outputAnnual losses & CO₂ emissions
17.90 tCO₂/yr
1000 kVA · S13 — oil-immersed (grade 3) · 50% load · 8760 h · 0.6 tCO₂/MWh
Load loss
10300 W
Annual losses
29,828 kWh
Efficiency
99.32%
Loss & efficiency calculation
| No-load loss | 830 W × 8760 h = 7,271 kWh/yr |
| Load loss | 10300 W × (50%)² × 8760 h = 22,557 kWh/yr |
| Annual losses | = 29,828 kWh/yr |
| Efficiency | 4,380,000 ÷ (4,380,000 + 29,828) = 99.32% |
| CO₂ emissions | 29,828 kWh × 0.6 tCO₂/MWh ÷ 1000 = 17.90 tCO₂/yr |
Efficiency-level comparison (lowest CO₂ first)
| Efficiency level | Po | Pk | Loss/yr | CO₂/yr |
|---|---|---|---|---|
| Amorphous alloy — oil-immersed | 270 W | 10300 W | 24,922 | 14.95 |
| S20 — oil-immersed (NX1) | 450 W | 9600 W | 24,966 | 14.98 |
| S13 — oil-immersed (grade 3) ◂ selected | 830 W | 10300 W | 29,828 | 17.90 |
| SCB13 — dry-type | 1200 W | 9600 W | 31,536 | 18.92 |
| S11 — oil-immersed (grade 3) | 1150 W | 10300 W | 32,631 | 19.58 |
Carbon insight
Upgrading from "S13 — oil-immersed (grade 3)" to the lowest-carbon "Amorphous alloy — oil-immersed" would avoid ≈ 4,906 kWh and ≈ 2.94 tCO₂ per year at this load factor — subject to the actual nameplate losses and the local grid emission factor.
Note
Losses use typical values (GB 20052 / industry references) scaled from 1000 kVA — always verify against the nameplate. Output energy assumes PF = 1 (kVA × PF × load factor × hours). The grid emission factor varies by region (≈0.2–1.0 tCO₂/MWh); adjust it to your local grid for a meaningful result.
For ESG, energy-audit and plant engineers quantifying transformer losses and carbon footprint, and justifying a higher-efficiency transformer.
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Worked example
A pre-computed reference example (crawlable — no JavaScript required). Enter your own parameters above for a live result.
Example 1 — S13 1000 kVA at 50% load
Annual losses & CO₂ emissions
17.90 tCO₂/yr
1000 kVA · S13 — oil-immersed (grade 3) · 50% load · 8760 h · 0.6 tCO₂/MWh
No-load loss
830 W
Load loss
10300 W
Annual losses
29,828 kWh
Efficiency
99.32%
Loss & efficiency calculation
| No-load loss | 830 W × 8760 h = 7,271 kWh/yr |
| Load loss | 10300 W × (50%)² × 8760 h = 22,557 kWh/yr |
| Annual losses | = 29,828 kWh/yr |
| Efficiency | 4,380,000 ÷ (4,380,000 + 29,828) = 99.32% |
| CO₂ emissions | 29,828 kWh × 0.6 tCO₂/MWh ÷ 1000 = 17.90 tCO₂/yr |
Efficiency-level comparison (lowest CO₂ first)
| Efficiency level | Po | Pk | Loss/yr | CO₂/yr |
|---|---|---|---|---|
| Amorphous alloy — oil-immersed | 270 W | 10300 W | 24,922 | 14.95 |
| S20 — oil-immersed (NX1) | 450 W | 9600 W | 24,966 | 14.98 |
| S13 — oil-immersed (grade 3) ◂ selected | 830 W | 10300 W | 29,828 | 17.90 |
| SCB13 — dry-type | 1200 W | 9600 W | 31,536 | 18.92 |
| S11 — oil-immersed (grade 3) | 1150 W | 10300 W | 32,631 | 19.58 |
Carbon insight
Upgrading from "S13 — oil-immersed (grade 3)" to the lowest-carbon "Amorphous alloy — oil-immersed" would avoid ≈ 4,906 kWh and ≈ 2.94 tCO₂ per year at this load factor — subject to the actual nameplate losses and the local grid emission factor.
Note
Losses use typical values (GB 20052 / industry references) scaled from 1000 kVA — always verify against the nameplate. Output energy assumes PF = 1 (kVA × PF × load factor × hours). The grid emission factor varies by region (≈0.2–1.0 tCO₂/MWh); adjust it to your local grid for a meaningful result.
Example 2 — S20 630 kVA at 60% load
Annual losses & CO₂ emissions
12.02 tCO₂/yr
630 kVA · S20 — oil-immersed (NX1) · 60% load · 8760 h · 0.55 tCO₂/MWh
No-load loss
318 W
Load loss
6048 W
Annual losses
21,861 kWh
Efficiency
99.34%
Loss & efficiency calculation
| No-load loss | 318 W × 8760 h = 2,788 kWh/yr |
| Load loss | 6048 W × (60%)² × 8760 h = 19,073 kWh/yr |
| Annual losses | = 21,861 kWh/yr |
| Efficiency | 3,311,280 ÷ (3,311,280 + 21,861) = 99.34% |
| CO₂ emissions | 21,861 kWh × 0.55 tCO₂/MWh ÷ 1000 = 12.02 tCO₂/yr |
Efficiency-level comparison (lowest CO₂ first)
| Efficiency level | Po | Pk | Loss/yr | CO₂/yr |
|---|---|---|---|---|
| S20 — oil-immersed (NX1) ◂ selected | 318 W | 6048 W | 21,861 | 12.02 |
| Amorphous alloy — oil-immersed | 191 W | 6489 W | 22,136 | 12.17 |
| S13 — oil-immersed (grade 3) | 587 W | 6736 W | 26,383 | 14.51 |
| SCB13 — dry-type | 849 W | 6048 W | 26,506 | 14.58 |
| S11 — oil-immersed (grade 3) | 813 W | 6489 W | 27,587 | 15.17 |
Carbon insight
"S20 — oil-immersed (NX1)" is the lowest-carbon option in this comparison.
Note
Losses use typical values (GB 20052 / industry references) scaled from 1000 kVA — always verify against the nameplate. Output energy assumes PF = 1 (kVA × PF × load factor × hours). The grid emission factor varies by region (≈0.2–1.0 tCO₂/MWh); adjust it to your local grid for a meaningful result.
How it was calculated
- · No-load loss energy = Po × hours; load loss energy = Pk × LF² × hours.
- · Annual losses = Po × hours + Pk × LF² × hours.
- · Efficiency = output ÷ (output + losses), output = kVA × LF × hours.
- · CO₂ emissions = annual losses × grid emission factor.
- · Losses scale from the 1000 kVA reference by Po ∝ S^0.75, Pk ∝ S.
Referenced standards
| Standard | Scope |
|---|---|
| IEC 60076 | Power transformers |
| GB 20052 | Minimum allowable values of energy efficiency and energy efficiency grades for power transformers |
| IEC 60364-8-1 | Low-voltage electrical installations — energy efficiency |
| ISO 14064-1 | Greenhouse gases — quantification and reporting of emissions |
Frequently asked questions
How do I calculate transformer CO2 emissions?
CO2 = annual losses (kWh) x grid emission factor. No-Load Loss runs 24/7: a 1000 kVA unit with 1.2 kW no-load loss consumes 10,512 kWh/yr just sitting energised. At a 0.5 kg/kWh grid factor that is ~5.3 t CO2/yr. The calculator sums no-load and load losses and converts to carbon.
What efficiency level should a transformer meet?
Distribution transformers are 98-99.5% efficient at full load. GB 20052 and IEC 60076-20 set minimum efficiency/loss grades; choosing a higher grade (S13/S20, SCB13/SCB14) cuts no-load loss 20-40%. The calculator compares efficiency levels and their loss and CO2 impact.
How much energy does a transformer waste in a year?
A 1000 kVA Transformer at 50% load with 1.2 kW no-load and 8 kW full-load loss wastes about 1.2x8760 + 8x0.25x8760 = 28,032 kWh/yr. A lower-loss S13 model can cut that 15-25%. The calculator quantifies annual losses and their cost.
What is a good load factor for transformer efficiency?
Peak efficiency occurs where load loss equals no-load loss, often 40-60% loading for distribution transformers. Operating far below this wastes no-load loss; far above raises Copper Loss. The calculator shows the efficiency curve and the optimal loading point.
How do I compare two transformers on lifetime carbon?
Compare annual losses x lifetime x grid factor, plus embodied carbon from materials (copper, steel, oil). The loss-driven operational carbon usually dominates over 20-30 years. The calculator computes operational CO2 per model so you can rank S11 vs S13 vs amorphous.
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Results are engineering estimates for preliminary design and reference only. Always verify with the applicable standards, the equipment nameplate and a licensed engineer before procurement or installation.
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